If you have a budget available, you can use a tool like UX Recorder, which records your phone's screen and syncs with the front camera. The downside is that it is only available for iPhone and works like a lie browser—not for testing apps.
Make sure that the application records the location where the person touched the screen. This helps a lot in analyzing the video later:
- It is not invasive; there is no other camera pointed at the participant
- The video is good; you can see clearly what happens on the screen
- The person can move at will with the cell phone
- You cannot see the user's finger and the gestures that the person makes with their hand (at most, the program signals the place ...