How can I make it so that when one object is touched, it can be moved? But when it is released from any contact from other objects, it sits still in its position?

I am using a Leap Motion with the pinch function and I need it so that an object will stay in the position it's in, but when grabbed, it then can move. When it is released, it goes back into its motionless state. Also while I'm at it, would I be able to get the script to attach to an object to be able to turn on and off the pinch mode? So that when I place objects, I don't accidentally move it. That would be awesome!