<?php
   $result = array(
       'State'   => 'Done',
       'ID'        => 1
   );

   wp_send_json( $result );
?>

$( '#contact_form' ).bootstrapValidator({
    fields: {
        // ...
    },
    submitHandler: function( formInstance ) {
        $.post( "../send-message", $("#contact_form").serialize(), function( result ) {
            alert( result );
        });
    }
});