Recently when I pick up my iPhone 7 Plus (especially when it is charging), there was some kind of vibration that felt like a turning gyroscope which I played when I was a kid. And then after picking up the phone for 10, 20 seconds, the vibration would stop. What was it about? If it was a gyroscope, what was it turning for?
i think it's Taptic Engine. This engine can turned off.
If you like to disable go to Settings -> Sounds & Haptics - > System Haptics -> turn off.
Taptic Engine is different from 3D Touch. So disabling haptics won’t turn off 3D touch.