Adding Vibrate to Alarms?

[PiggyMiddle]

Hi, I am using two daily alarms for meds and sometimes if there is some ambient noise, I can't hear the alarm go off with the 520 in my back pocket.

I can't find a way to add Vibrate to the Alarm.

Is it possible?
How?

I mostly wear tees, so back pocket, it must be.

Thanks