How to provide the listener support like in EventTrigger?

Hello!
For EventTrigger I can choose methods from other scripts like listeners of events. I can do it just in the inspector.
How can I realize it in a custom script to choose callback methods and their arguments just in the inspector?

UnityEvent is a wonderful class. Make a public one and it’ll just work. And you can use UnityEvent to accept a string parameter, etc.