It goes in the pressure cooker with the bone from the ham and any other trimmings, as well as whatever jellied/caramelized juices comes out of the ham into the pan that you bake it in. Plus a bit of onion and garlic. I am a fan of
very long cook times when making bone broth, even in a pressure cooker. At least two hours, and more is better.
Every bone-in ham we've cooked so far has yielded enough scrap to make at least 4 quarts of good rich bone broth.