My last two projects at Megacorp (now 6 years ago) were working on products used to store the data harvested from all sorts of inputs. Phones. Traffic cams. License Plate Readers (LPRs). Military (now Police) surveillance systems. Social Media. If it was digital, my product stored it, processed it for metadata ("data about the data") and then indexed the metadata. Exabytes of it. It's been 6 years since so it's probably orders of magnitude beyond that now.
Non-disclosure/confidentiality agreements are still in place under threat of clawing back my severance pay... (but then you can't get blood out of a turnip). There were several times after reviewing big brother like use cases for the product that I felt like I needed to take a shower after.
Add in the modern AI filters that have become available since I left MegaCorp and SkyNet becomes another future-scifi-becomes-todays-reality. When the CEO was asked if AI and these big-brother enabling products were ethical, her response was "if we don't build it somebody else will".
The TL/DR version: futuristic TV shows like Person of Interest and some aspects (omit the psychic aspects) of Minority Report are not fiction.
Some short examples of what is common place today:
* Its not just what Google or few other big name monitors from your device and web history. Install a browser add-on that shows the number of ad-trackers on a given webpage. (This e-r.org page I'm typing on now currently shows 41 different trackers). Law enforcement doesn't need to get a search warrant to obtain the data from Google, they can buy parts from any of these 3rd party trackers and glue it back together.
* People have been subject to police investigation because their phone data showed they were in the general vicinity of a crime scene. Research "geofence search warrant"
* A large metropolitan police department records all traffic cams and LPR data then keeps it on-line (immediately) accessible for 7 YEARS, after which it is moved to slower off-line storage such as tape or other archives. The metadata for each capture was larger than the image capture itself... date, time, location, plate data, color, driver description, passenger description... if it could be gleaned from a series of photos it was cataloged. When I say series of photos its not just 1 camera in one location. Data from multiple cameras from multiple intersections along the route the vehicle took are merged together.
* Existing stored data can be re-scanned for new keywords of interest, automatically, as frequently as you want. Yesterday's pancake syrup is tomorrows terrorist hate speech.
* voice data is converted to text (think youtube closed caption data, but government grade) and indexed for future search.
*A former friend of mine has an Amazon Alexa in their kitchen. You say "Alexa, X" and the device lights up and responds. However, it doesn't just activate on the word "Alexa". We were having a dinner conversation when I mentioned a now politically incorrect restaurant name (Sam_os) and the Alexa activated. We repeated the word a couple of times and the device triggered multiple times... Its listening ALL THE TIME.
* Google "zuckerburg laptop" (head of facebook) and there are images that he puts tape over the laptop camera...
https://www.nytimes.com/2016/06/23/...laptop-camera-you-should-consider-it-too.html
* MegaCorp bought the research project software that was being used by one of the secretive gov agencies to track terrorists and commercialized it for use by local police departments. I got a demo of it as part of a job interview... the capabilities TV show Person of Interest is available for purchase today.
* new cars have the more tech than your phone... so leaving your phone home doesn't do any good.
To get back to the specific question use case of your phone: It has robust sensor suite built in... GPS (rate of change in location = speed traveled), cameras, microphones, accelerometer, gyroscope, magentometer, ambient light sensors, and biometric sensors. LiDAR (room mapping) is on some tablets and expect to appear in iPhones. Are you really comfy with all of that data being accumulated?
I could go on but this is too long already. Extrapolate the current societal "I'm right and you're evil" out another 10 years or so and layer in a social credit score. To paraphrase Miranda: "Anything you say can be used against you".