/** * Add checkbox **/ add_action('woocommerce_after_order_notes', 'wpm_checkout_field'); function wpm_checkout_field( $checkout ) { echo 'Checkbox'; woocommerce_form_field( 'wpm_cb', array( 'type' => 'checkbox', 'class' => array('input-checkbox'), 'label' => __('Check here.'), 'required' => true, ), $checkout->get_value( 'wpm_cb' )); }