Check if any post is bookarked by any post by id for CBX Bookmark for Wordpress https://codeboxr.com/documentation-for-cbx-bookmark-for-wordpress/

gistfile1.txt

if(class_exists('CBXWPBookmarkHelper')){
  $post_id = ''; put post id here
  //check if post is bookmarked once for post id $post_id
  $is_bookmarked = CBXWPBookmarkHelper::isBookmarked($post_id);   
  //is_bookmarked is true or false
}