The garbage disposal either has something caught in it or the unit itself has a problem. Turn power to unit off. With a flashlight, look down the gb. You should see some small pieces of metal that are attached to the grinding disc (fly wheel). These are the impellers and they should swing freely. If it is an old unit these may have worn out causing the noise , too. Sometime these impellers or blades get stuck throwing the gb out of balance. They may be freed up using a screwdriver and hammer. If not then
next, with your hand feel for any metal or hard object that may have become stuck in the unit. You should see, feel or find something that doesn't feel like it should be there. Take it out with needle nose pliers, etcs. If you just don't find anything, the unit bearings or motor could be worn out and we have found it is usually cheaper to replace than repair these units.