i want to make a gui button that when it it is held/pressed it will move the player right until released how do i do this?

this is my normal player movement script:

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{

    public Rigidbody prb;

    public float forwardForce = 1730f;
    public float sidewaysForce = 570f;
    
    private void FixedUpdate()
    {
        prb.AddForce(0, 0, forwardForce * Time.deltaTime);

        var InputForce = Input.GetAxis("Horizontal");
        prb.AddForce( InputForce * sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);

        if (prb.position.y < -1f)
        {
            GameManager.playerDead = true;
        }
        
        /*
        if (Input.GetKey("d"))
        {
            prb.AddForce(sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
        }
        if (Input.GetKey("a"))
        {
            prb.AddForce(-sidewaysForce * Time.deltaTime, 0, 0, ForceMode.VelocityChange);
        }
        */
        
    }
}

how do i make it so it works with a button?

i need so it will be playable on the phone