Add reCaptcha v2 to WooCommerce Checkout

checkout-functions.php

<?php
/**
 * Add reCaptcha to checkout form
 * Note: Can't place within the payment part of the form, WooCommerce just won't show it, choose an appropriate action to add it to accordingly
 * @param $checkout
 */
function doublee_show_me_the_checkout_captcha($checkout) {
	echo '<div class="g-recaptcha" data-sitekey="YOUR_KEY_HERE"></div>';
}
add_action('woocommerce_checkout_order_review', 'doublee_show_me_the_checkout_captcha', 18);


/**
 * Validate reCaptcha
 */
function doublee_process_recaptcha() {

	$postdata = $_POST['g-recaptcha-response'];
	$verified_recaptcha = file_get_contents('https://www.google.com/recaptcha/api/siteverify?secret=YOUR_KEY_HERE&response='.$postdata);
	$response = json_decode($verified_recaptcha);

	if(!$response->success) {
		wc_add_notice('Please verify that you are not a robot' ,'error');
	}
}
add_action('woocommerce_checkout_process', 'doublee_process_recaptcha');

enqueue.php

<?php
wp_enqueue_script('recaptcha', '//www.google.com/recaptcha/api.js', '', '', true);