How do I make a rigidbody 3D wall jump?

So I've made a simple third person parkour script, and want to implement wall jumping, and I'm not sure how to go about doing it.
Here's how I detect wall collision:

void OnCollisionEnter(Collision collision)

     foreach (ContactPoint contact in collision.contacts)
     {
         if (!onGround && rb.position.y > -16f)
         {
             Debug.DrawRay(contact.point, contact.normal, Color.red, 10f);
         }
     }
 }

And heres my movement script:

 void Update()
 {
     if (Input.GetKeyDown(KeyCode.Space) && onGround == true)
     {
         speed = jumpSpeed;
         onGround = false;
         rb.AddForce(jump * jumpForce, ForceMode.Impulse);
     }
 }

 void FixedUpdate()
 {
     moving = Input.GetKey(KeyCode.W) || Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.S) || Input.GetKey(KeyCode.D);

     if (moving)
     {
         transform.rotation = Quaternion.Euler(0, Camera.rotation.eulerAngles.y, 0);
     }

     float x = Input.GetAxisRaw("Horizontal");
     float y = Input.GetAxisRaw("Vertical");

     Vector3 move = (transform.right * x + transform.forward * y);
     move.Normalize();
     rb.velocity = new Vector3(move.x * speed * Time.deltaTime, rb.velocity.y, move.z * speed * Time.deltaTime);

     onGround = Physics.CheckSphere(new Vector3(transform.position.x, transform.position.y - 1, transform.position.z), spSize, Ground);
 }

Any answers would be greatly appreciated, sorry if this is a stupid question I'm pretty new to Unity.