Q: Magnet stuck on spark plug.

I do not have a vehicle listed so I am not sure how to guide you. but depending on the location of the spark plug hole, he may be able to use needle nose pliers to go into the hole and try to retrieve the parts. Some parts stores or hardware stores will sell a long enough pair of needle nose pliers or long tweezers that can fit into the hole to grab the parts. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look in an effort to help out. Refrain form trying to drive the vehicle until the parts are pulled out to avoid engine damage.