CSHARP

unity detect object with raycast

 using UnityEngine;
 
 public class Raycaster : MonoBehaviour {
     void Update() {
         RaycastHit hit;
         if (Physics.Raycast(transform.position, -Vector3.up, out hit))
             hit.transform.SendMessage ("HitByRay");
         
     }
 }
 
 //The object would have a script like this:

 using UnityEngine;
 
 public class ObjectHit : MonoBehaviour {
     void HitByRay () {
         Debug.Log ("I was hit by a Ray");
     }
 }