Hi Paul,
Yes, you can use this filter for any field, it is the HTML input of the field and is not affected by the value of the field (saved in a custom table or not).
add_filter( 'rwmb_fieldID_html', function( $field_html, $field, $meta ) {
$field_html .= '<p>Add your HTML code here</p>';
return $field_html;
}, 10, 3 );