how to check if the post id has a new comment?

There is a WordPress hook comment_post to retrieve recently added comment and to pass comment id to get_comment you will get the post id.

add_action( 'comment_post', 'show_message_function', 10, 2 );

function show_message_function( $comment_ID, $comment_approved ) {

  $comment_array = get_comment($comment_ID );  

  $comment_post_id = $comment_array->comment_post_ID; 
}