iPhones (and iPads) may also vibrate randomly when they receive emergency or government alerts. Depending on the emergency alert, your iPhone will make a random alarm sound and vibrate until you view or dismiss the alert. Additionally, faulty or broken charging accessories can trigger incessant vi...
such as when you touch and hold an app icon or scroll through a list. Even if Do Not Disturb is on, your iPhone will still vibrate for System Haptics if you have enabled it. To disable System Haptics, go to Settings > Sounds & Haptics and turn off System Haptics. ...
While you have the Control Center open on the Apple Watch, there are a few other items to pay attention to. One is the moon icon. If you tap that icon it will put the watch into Do Not Disturb mode, which will stop all sounds, as well as prevent the vibrate part of an alert or...