How to implement pagination on a custom WP_Query Ajax

I want to paginate my WordPress posts in a custom loop with Ajax, so when I click on load more button posts will appear.

My code:

<?php 
    $postsPerPage = 3;
    $args = array(
        'post_type' => 'post',
        'posts_per_page' => $postsPerPage,
        'cat' => 1
    );
    $loop = new WP_Query($args);

    while ($loop->have_posts()) : $loop->the_post();
?>
<h1><?php the_title(); ?></h1>
<p>
    <?php the_content(); ?>
</p>
<?php
    endwhile; 
    echo '<a href="#">Load More</a>';
    wp_reset_postdata(); 
?>

This code does not paginate. Is there a better way to do this?