images - How to display a shortcode caption somewhere other than the_content in WordPress

Try this:

$caption_info = array();
add_filter( 'img_caption_shortcode', 'capture_caption', 10, 3 );
function capture_caption( $blank = '', $attr, $content ) { global $caption_info; $caption_info[] = array('attr' =>
 $attr, 'content' =>
 $content ); return ' ';
}

It will save info from all captions into global $caption_info variable and suppress their display in content (space is returned because filter result is ignored if empty).