The Self-Playing Harp is a foundable in Harry Potter: Wizards Unite and can be found in the Wonders of the Wizarding World registry. It has a medium threat level.
Summary[]
In his search for the Philosopher's Stone, Professor Quirinus Quirrell enchanted a harp to play on its own to induce Fluffy the Cerberus into sleep. Quirrell was then able to sneak past the sleeping beast.