PruebaEditor.cs

using UnityEngine;
using UnityEditor;
using UnityEditor.SceneManagement;

[CustomEditor(typeof(Prueba))]
public class PruebaEditor : Editor {
    Prueba Target { get => (Prueba) target; }

    void OnSceneGUI () {
        Ray rayo = HandleUtility.GUIPointToWorldRay(Event.current.mousePosition);
        Debug.DrawLine(rayo.origin, rayo.origin + rayo.direction * 100);
        RaycastHit hit;

        Target.didHit = Physics.Raycast(rayo, out hit);
        bool isClicking =
            Event.current.type == EventType.MouseDown &&
            Event.current.button == 0 ||
            Event.current.type == EventType.MouseDrag;

        if (Target.didHit && isClicking) {
            GUIUtility.hotControl = GUIUtility.GetControlID(FocusType.Passive);
            Event.current.Use();

            Target.hitName = hit.collider.name;
            Target.hitPoint.transform.position = hit.point;
        }

    }
}