You might be looking for the "ENTITY:Use" hook, which has the same name as this method.
+use action on an entity.
1 Entity activator
The entity that caused this input. This will usually be the player who pressed their use key
2 Entity caller = NULL
The entity responsible for the input. This will typically be the same as
activatorunless some other entity is acting as a proxy
4 number value = 0