ray to click | unity3d

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

public class BuildManager : MonoBehaviour
{
    public Camera mainCam;

    public GameObject prevObj;
    public GameObject currObj;

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.Mouse0))
        {
            clickToGrid();
        }
    }

    private void clickToGrid()
    {
        Vector3 pos = new Vector3(Input.mousePosition.x, Input.mousePosition.y, 0);
        Ray ray = mainCam.ScreenPointToRay(pos);

        RaycastHit hit;

        Debug.DrawRay(ray.origin, ray.direction * 10, Color.yellow);

        if (Physics.Raycast(mainCam.ScreenPointToRay(pos), out hit, 10))
        {
            Debug.Log(hit.transform.name);
        }
    }
}