Add custom text field to checkout form

add_action('woocommerce_after_checkout_billing_form', 'custom_checkout_form_field');
function custom_checkout_form_field($checkout) {
    echo '<div id="custom_checkout_field"><h2>' . __('Zusätzliche Informationen') . '</h2>';
    woocommerce_form_field('custom_field', array(
        'type' => 'text',
        'class' => array('form-row-wide'),
        'label' => __('Benutzerdefiniertes Feld'),
        'placeholder' => __('Geben Sie hier Ihre Informationen ein.'),
        'required' => false,
    ), $checkout->get_value('custom_field'));
    echo '</div>';
}