How Can I Move My Player With Camera Direction And Without Using Get Axis??

hello people i hope y'all doing fine, i know that the title wasn't that obvious but basically i want to move my fps player to the direction that the camera is facing for example when i press the W key the player should move forward acording to the direction he's looking at, how ever thats not the problem here i managed to find a solution after all, but the problem is as you can see in the code im using get axis which mean the movement keys are by default ARROWS and WASD and i want to change the keys To what ever i want without having to go to project setting and change get axis settings, so i tried to use GET KEY and it does not work what can i do to make it work?? again im sorry if the question is not that obvious and here is the code im using :

 public float movespeed;
 public Transform tr;
 public Rigidbody rb;
 public CharacterController charactercontroll;

 public float rotation_speed;
 private float mousex;

 
 void Update()
 {
     

     mousex += Input.GetAxis("Mouse X") * Time.deltaTime * rotation_speed;
     
     tr.rotation = Quaternion.Euler(0, mousex, 0);


     
     //////////////////CHANGE THE GET AXIS WITH GET KEY SOMEHOW 

     float horizontalmove = Input.GetAxis("Horizontal") * Time.deltaTime * movespeed;
     float verticalmove = Input.GetAxis("Vertical") * Time.deltaTime * movespeed;

     Vector3 updown = transform.forward * verticalmove;
     Vector3 rightleft = transform.right * horizontalmove;



     charactercontroll.SimpleMove(updown + rightleft);
     
 }

}