MouseControls.cs

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

public class MouseControls : MonoBehaviour
{
    public float speed;
    Vector3 mousePos;

    void Start()
    {

    }

    void Update()
    {
        mousePos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
        transform.LookAt(mousePos);
        transform.localEulerAngles = new Vector3(0, transform.localEulerAngles.y, transform.localEulerAngles.z);

        if (Input.GetMouseButton(0))
            transform.position += (-transform.position + mousePos).normalized * speed * Time.deltaTime;
        transform.position = new Vector3(transform.position.x, 0, transform.position.z);
    }
}