How to add a random number to my AddForce angle

I'm following a tutorial and there is a part where you add a force to an object when shooting it but it looks really unnatural so I am trying to add a random number to the angle of the AddForce.

 void Shoot()
     {
         muzzleFlash.Play();
 
         RaycastHit hit;
         if (Physics.Raycast(fpsCam.transform.position, fpsCam.transform.forward, out hit, range))
         {
             Debug.Log(hit.transform.name);
 
             Target target = hit.transform.GetComponent<Target>();
             if (target != null)
             {
                 target.TakeDamage(damage);
             }
 
             if (hit.rigidbody != null)
             {
                 hit.rigidbody.AddForce(hit.normal * impactForce);     //Here
             }
             
             GameObject impactGO = Instantiate(impactEffect, hit.point, Quaternion.LookRotation(hit.normal));
             Destroy(impactGO, 2f);
         }
     }
 
     public void RandomGenerate()
     {
         TheNumber = Random.Range(-10, 10);
     }
 }

I, unfortunately, don't know how to do this and simply adding TheNumber to hit.normal doesn't work. Any help is appreciated.