How To attach two rigid bodies using a hinge joint via script in game

working on a game an i have a prefab that shoots out and deletes its self after the fire button is released i need a way to make the prefab hinge to an object after it collides with an object. any help would be great. My script for shooting the object is this...

using UnityEngine; using System.Collections;

public class GrappleHookShoot : MonoBehaviour {

 public GameObject GrappleHook_prefab;
 public float grappleImpulse = 20f;
 public GameObject Player_prefab;

 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
     if (Input.GetButtonDown("Fire")){
         Camera cam = Camera.main;
         GameObject theGrapple = (GameObject)Instantiate(GrappleHook_prefab, cam.transform.position + cam.transform.forward, cam.transform.rotation);
         theGrapple.GetComponent<Rigidbody>().AddForce(cam.transform.forward * grappleImpulse, ForceMode.Impulse);
     }
     }
 }