function vacancy_render_apply_form(stdClass $vacancy = null)
{
    ctools_include('ajax');
    ctools_include('modal');
    ctools_modal_add_js();
    $form_state = array(
        'ajax' => TRUE,
        'title' => t('Vacancy'),
        'vacancy_id' => $vacancy->id
    );
    if(!empty($form_state['ajax_commands'])){
        $command = $form_state['ajax_commands'];
    }else {
        $command = ctools_modal_form_wrapper('vacancy_apply_form', $form_state);
    }
    print ajax_render($command);
    drupal_exit();
}

$items['vacancy/loadForm/%vacancy_id'] = array(
    'page callback' => 'vacancy_render_apply_form',
    'page arguments' => array(2),
    'access callback' => TRUE,
    'type' => MENU_CALLBACK
);

<a href="/vacancy/loadForm/<?php echo $v->id; ?>" class="ctools-use-modal">
        <div id="apply-button">APPLY</div>
    </a>