Most VU meters these days are actually DC meters, so they need a rectifier. And if you're going to use them you typically want a buffer to prevent noise, too.
The good news is you can get the meters dirt cheap, and scavenge them from battery testers, CB testers, and other old junk.
This PCB is a dead quiet, simple drop-in for any pedal, and should work with any DC meter. It provides a decorative dancing needle to your audio projects, but understand this isn't an ideal way to take measurements if accuracy is your goal.Get One Build Documentation