How can you remove a piece of a headphone out of a headphone jack?

There are a couple of things you can try..
1) dismantling the device you have the piece stuck in and push it out from the inside
2)If you cant pull it apart you can cut off the end of a cocktail stick, put a tiny piece of super glue in the centre making sure you don't get any on the edges. Then carefully poke that into the hole and hold it tight up against the tip that is stuck in there. Once you are sure the glue has dried you should then be able to pull it out.

Do this at your own risk....... If you do it wrong you can end up with a coctail stick glued into the socket as well