InspectorButton

 using UnityEditor;

using UnityEngine;

[CustomEditor(typeof(YourClassName))]

public class YourClassNameEditor : Editor

{

    public override void OnInspectorGUI()

    {

        YourClassName yourClassName = (YourClassName)target;

        if (GUILayout.Button("SayHi"))

        {

            yourClassName.SayHi();

        }

    }

}