HTML make h-captcha mandetory in a form

Question

Im trying to add H-captcha to my website Currently I have this code

<form action="/send" method="post">
    <div class="h-captcha" data-sitekey="sample" data-theme="dark"></div>
    <script src="https://js.hcaptcha.com/1/api.js" async defer></script>
</form>

However a user can just sumbit a form without a valid hcaptcha

How do I make my H-Captcha field required ?

Thanks for the help