Welcome to Massager app support.
It looks like your iPhone don’t vibrate, and we’d be happy to look into this with you.
Vibration doesn’t work when app is minimized, lock app instead of minimizing
To get started, please navigate to: Settings > Accessibility > Touch > Vibration. If it’s not enabled, tap to enable it, and let us know if that helps.

If vibration is already enabled, please try the following steps:
Go to: Settings > Sounds & Haptics, and turn off both “Vibrate on Ring” and “Vibrate on Silent”
Restart your iPhone: Restart your iPhone, iPad, or iPod touch
Go to: Settings > Sounds & Haptics, and turn on “Vibrate on Ring” and “Vibrate on Silent”
Test for vibration with the Silent switch on and off.