Example.cs

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

[InitializeOnLoad]
internal static class Example
{
    static Example()
    {
        SceneView.beforeSceneGui -= OnDuringSceneGui;
        SceneView.beforeSceneGui += OnDuringSceneGui;

        static void OnDuringSceneGui( SceneView sceneView )
        {
            var position                = Event.current.mousePosition;
            var currentDrawingSceneView = SceneView.currentDrawingSceneView;
            var camera                  = currentDrawingSceneView.camera;

            position.y = camera.pixelHeight - position.y;
            position   = camera.ScreenToWorldPoint( position );
            position.y = -position.y;

            var outObjectList = new List<Object>();
            HandleUtility.GetOverlappingObjects( position, outObjectList );

            foreach ( var outObject in outObjectList )
            {
                Debug.Log( outObject );
            }
        }
    }
}