How to play sound with mouse movement/mouse look?

I can't find help for this anywhere, I have been looking forever... also I'm new to scripts and Unity so any help would be great!

What I have is a gun turret that is controlled by the mouse. It controls the gun left/right and up/down in a stationary position.

What I would like is a sound to play when you look around pointing the gun. The sound would be an electric motor type groin. Think of a planes landing gear going up and down. Preferably when you stopped moving the mouse the turret would not stop instantly but rapidly slow to a stop and the sound would wind down. Then wind up again when you moved.

So How do I get the movement not to stop/start with the mouse exactly but slowly come to a start/stop and most importantly how do I get a sound to play when I move the mouse/turret?

Thanks for your time!