how to use belongsto in laravel code example

Example 1: laravel belongs to

public function user()
    {
        return $this->belongsTo(User::class);
    }

Example 2: laravel belongs to

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Phone extends Model
{
    /**
     * Get the user that owns the phone.
     */
    public function user()
    {
        return $this->belongsTo('App\Models\User');
    }
}