PlayerBall.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerBall : MonoBehaviour
{
    [SerializeField]
    private float rotSpeed = 100;

    [SerializeField]
    private float moveSpeed;

    private Vector2? oldMousePos;

    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        transform.Rotate(Time.deltaTime * rotSpeed,0,0);

        var speed = 0.0f;
        if (Input.GetMouseButtonDown(0))
        {
            oldMousePos = Input.mousePosition;
        }
        if (Input.GetMouseButton(0) && oldMousePos.HasValue)
        {
            speed = oldMousePos.Value.x - Input.mousePosition.x;
            oldMousePos = Input.mousePosition;
        }
        else
        {
            oldMousePos = null;
        }
       
        transform.position += new Vector3(Time.deltaTime * speed * moveSpeed,0,0);
    }
}