Description

Callback that is triggered after any undo or redo event.

using UnityEditor;
using UnityEngine;

public class ExampleUndoRedoEventScript : MonoBehaviour
{
    void Start()
    {
        Undo.undoRedoEvent += OnUndoRedoEvent;
    }

    void OnDestroy()
    {
        Undo.undoRedoEvent -= OnUndoRedoEvent;
    }

    void OnUndoRedoEvent(in UndoRedoInfo info)
    {
        // code for the action to take on Undo or Redo event
    }
}