How is gripper action realized?

Hello. I’m writing a plugin for my use case and I want to place a marker on the map when gripper is released. I have learnt about qml and plugin functionalities and found out how to place a marker on the map just fine.
What I couldn’t find yet is how the gripper works. I’m planning a flight that includes an advanced waypoint gripper release, in which I want to place a marker to exact point when the item is dropped succesfully by releasing gripper.
I think it is a mavlink command but I couldn’t find where to catch it or process it. I also don’t know how to make it into plugin. If anybody can provide guidance that would be great.

Thanks for reading.