Hi Roberto,
Thanks for your question.
First, the vibration: Have you tried recording a custom vibration (choose Settings > Sounds, touch the ringtone or whatever in the Sound and Vibration
Patterns area, then Vibration > Custom)? A longer vibration or more distinctive rhythm might give you a better chance of feeling it.
Also, are you using a case that damps the vibration? Any heavy-duty case is likely to take out some of the intensity.
I don't know of a way to turn up the vibration motor to 11.
Second, on recording the drums -- here are three things to try, in ascending order of seriousness and cost:
1. Use a recorder app in which you can set the input level. (I like the FiRe apps.)
2. Use an external microphone rather than the iPhone's microphone.
3. Connect multiple microphones to an audio interface, then connect the interface to your iPhone and record it.
Best,
Guy