touch input

hello i want the script to work with touch how can i??
this script to rotate the player around the knob sprite by the left and right arow keys

Code (CSharp):

1. public float moveSpeed = 600f;
2.  
3.     float movement = 0f;
4.  
5.     // Update is called once per frame
6.     void Update()
7.     {
8.         movement = Input.GetAxisRaw("Horizontal");
9.     }
10.  
11.     private void FixedUpdate()
12.     {
13.         transform.RotateAround(Vector3.zero, Vector3.forward, movement * Time.fixedDeltaTime * -moveSpeed);
14.     }