get_the_post_thumbnail_caption

WordPress Version: 4.6

/**
 * Returns the post thumbnail caption.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return string Post thumbnail caption.
 */
function get_the_post_thumbnail_caption($post = null)
{
    $post_thumbnail_id = get_post_thumbnail_id($post);
    if (!$post_thumbnail_id) {
        return '';
    }
    $caption = wp_get_attachment_caption($post_thumbnail_id);
    if (!$caption) {
        $caption = '';
    }
    return $caption;
}