The metal strap on my band/watch vibrates or makes abnormal noise when there is an incoming call or a message

When a call or message comes in on your band/watch, the motor of your device will vibrate, causing the components of the metal strap to slightly vibrate and generate sound. This is normal. If this causes inconvenience to you, go to Settings > Sounds & vibration on your device, and set the notification volume and vibration level for incoming calls and messages to the appropriate values.