How to raycast always in direction of a object?

If you have a origin point you're raycasting from, you create a vector pointing in the correct direction by subtracting the origin's point from the target's point. If you're raycasting from the object that the script is attached to, it's simply:

 void RaycastTowardsThing(GameObject thing) {
     Vector3 raycastDir = thing.transform.position - transform.position;

     Physics.Raycast(transform.position, raycastDir, ...
 }

 private void Update()
 {
     RaycastHit hit;

     // Cast from the objects position upwards
     Physics.Raycast(transform.position, transform.up, out hit);
     // Cast from the objects position right
     Physics.Raycast(transform.position, transform.right, out hit);
     // Cast from the objects position forward
     Physics.Raycast(transform.position, transform.forward, out hit);
 }

@baste's solution should work. but I have a similar solution in my current game that is causing an issue when i rotate my transform.

What I am going for is i want the game object to rotate in accordance with the surface normal of the cube, (basically I am trying to walk on all sides of a cube and rotate accordingly. ) My first rotation works beautifully, but the raycast always points out in a different direction and therefore never hits the gameobject again, which prevents me from being able to reorient properly.

Here is my code, if anyone has any ideas as to what I am doing wrong I would appreciate the help. Really scratching my head as to what I am missing.

 using UnityEngine;
 using System.Collections;
 
 public class OrientToSurfaceNormal : MonoBehaviour
 {
 
     public Transform worldToStickTo;
     public float gravity = -9.8f;
 
     // Raycast stuff
     public Vector3 playerNormal;
     public Vector3 surfaceNormal;
     public Vector3 fwd;
     Vector3 direction;
     
     
     
     // Use this for initialization
     void Start()
     {
         playerNormal = transform.up;
         surfaceNormal = playerNormal;
     
     }
 
     // Update is called once per frame
     void FixedUpdate()
     {
         RaycastHit hitInfo;
 
         fwd = transform.TransformDirection((worldToStickTo.transform.position - transform.position));
         
         Physics.Raycast(transform.position, fwd, out hitInfo, 100); // THIS WORKS
         Debug.DrawRay(transform.position, fwd, Color.green);  // draw the debug;
 
         playerNormal = hitInfo.normal;
     }
 
     void Update()
     {
         transform.rotation = Quaternion.FromToRotation(surfaceNormal, playerNormal) * transform.rotation; // Rotation without smoothing. 
     }