Hello.
I installed a CAPTCHA in my contact form. But it is placed curiously.
See: http://www.philippedeletree.fr/page/contact/
(Google Translate)

I believe this may be basically theme (CSS) dependend. The theme's author @vincent3569 may be able to help here.

It looks okay on our own site: https://www.zenphoto.org/pages/contact/

In the meantime you can try to add the following to the zpBootstrap.css file:

.g-recaptcha {
  display: inline-block;
}

Note that you also need a private and public key to display the reCaptcha.

I think the captcha would not show if those keys weren't present already.

Thank you for your answers.
I added :
.g-recaptcha {
display: inline-block;
}
as shown and the captcha is positioned correctly.
(I have the public and private keys of google)
Thank you for your help.