Why does my iOS device beep and vibrate even after turning off "sounds" in every app?
It turns out that there is one app that does not have a "Sounds" setting, but still produces sounds and vibrations: Calendar. It's easy to overlook the all-important setting "Calendar Alerts." Tap that, tap vibrate, scroll all the way to the bottom, and set vibration to "None." That should solve it.

Here's your problem right here:



Just turn vibration off:



That's right!