Lightbox with Caption

i do not want to have a caption under the image itself – only as a caption to the lightboxed image so i found
this here from Josue:
https://kriesi.at/support/topic/show-captions-in-a-wordpress-gallery/#post-331052

and i changed it to:

function gallery_title_fix(){
?>
<script>
(function($){
    $(window).load(function() {
    	$('.lightbox-added img').each(function(){
            var lin = $(this).attr('alt');
            $(this).attr('title',lin);
        });
    });
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'gallery_title_fix');

is it possible to take not the attachement alt text but f.e. the attachment_caption or the attachment_content