Let's say you have a function called MyFunction, and you want to show a button in the inspector to trigger it.
Just add a "decoy" variable with the [ButtonInvoke] attribute in your script (type of the variable doesn't really matter, but its name will be used as button text.
// "MyFunction" is the name of the function you want to trigger
[ButtonInvoke("MyFunction")] public bool testMyFunction;
// OR use "nameof" to prevent typos