Super einfach - wie reCAPTCHA & hCaptcha!
<script src="https://unpkg.com/@berlinsms/plain-js-captcha/dist/bsms-captcha.js?sitekey=YOUR-KEY&callback=onCaptchaSuccess"></script>
<div class="bsms-captcha-container" data-sitekey="YOUR-SITEKEY" data-callback="onCaptchaSuccess"></div>