function yourFunction( $post_id ) {

    $yourTitle = get_post_field( post_title, $post_id, display );
 
    update_post_meta( $post_id, 'yourCustomField', $yourTitle );
}
 
add_action( 'wpuf_add_post_after_insert', 'yourFunction' );
add_action( 'wpuf_edit_post_after_update', 'yourFunction' );

Finally!
Thank you, DenisCGN, your code works for me!

Just a more little question:
– How can I update a field from another, if the original field is a date with YY/MM/DD HH:MM format and I need to update with only YYMMDD format?

[php]
$prev_date = ‘2013/12/07 12:12’;
$new_format = date(‘Ymd’, strtotime($prev_date) );
[/php]