How to make a smooth crosshair-animation in Unity3D?

Hi,

in Unity 3D I'd like to create a crosshair for my top-down 2D-shooter that gradually moves to its target whenever the player has the same x-position as the target.

The problem is that I want a smooth animation when the crosshair moves to the target. I have included a small gif from another game that shows a crosshair I'd like to achieve. Have a look at it: crosshair-video

I tried to do that with the following script but failed - the crosshair jumps forth and back when the enemies appear. It doesn't look so smooth like in the video I mentioned above. Any help, please?

The following script is attached to the player:

  [SerializeField]
  private GameObject crosshairGO;
  [SerializeField]
  private float speedCrosshair = 100.0f;

  private Rigidbody2D crosshairRB;
  private bool crosshairBegin = true;

  void Start () {

 crosshairRB = crosshairGO.GetComponent<Rigidbody2D>();
 crosshairBegin = true;
  }


  void FixedUpdate() {
 //Cast a ray straight up from the player
 float _size = 12f;
     Vector2 _direction = this.transform.up;
     RaycastHit2D _hit = Physics2D.Raycast(this.transform.position, _direction, _size);

     if (_hit.collider != null && _hit.collider.tag == "EnemyShipTag") {
         // We touched something!
         Debug.Log("we touched the enemy");
     
         Vector2 _direction2 = (_hit.collider.gameObject.transform.position - crosshairGO.transform.position).normalized;
         crosshairRB.velocity = new Vector2(this.transform.position.x, _direction2.y * speedCrosshair);
         crosshairBegin = false;
     } else {
         // Nothing hit
         Debug.Log("nothing hit");
         crosshairRB.velocity = Vector2.zero;
         Vector2 _pos2 = new Vector2(this.transform.position.x, 4.5f);
         if (crosshairBegin) crosshairGO.transform.position = _pos2;
     }
 }