Turn off vibration for calls, alerts, and system feedback so your iPhone stays completely still and silent.
Tap the Settings app, then tap Sounds & Haptics. This screen controls both ringtone vibration and the small haptic taps the system makes.
Tap Haptics (on older iOS versions this is a set of vibration toggles) and choose Don't Play so the phone never vibrates for rings or alerts, even in silent mode.
Back on the Sounds & Haptics screen, scroll down and switch off System Haptics to stop feedback taps for controls, switches, and interactions. Turn off Keyboard Feedback's Haptic option there as well if typing buzzes.
If only one thing buzzes, edit it directly: in Clock, tap the alarm, tap Sound, then Haptics, and choose None. Individual ringtones and text tones have the same Haptics option under Settings, Sounds & Haptics.
Flip the phone to silent and have someone call you, or set a short timer, to confirm nothing vibrates. If it still buzzes, check Accessibility, Touch, Vibration — turning that master switch off disables all vibration, including emergency alerts.