Can I use a Re-Captcha in a webform?

Yes - you can enable the Re-Captcha by ticking the "Use Re-Captcha" option in the Submit Settings of your form.

NOTE: Make sure that you have set up a failure view in your Dynamic View component so you can redirect to this view if the user does not use the Re-Captcha. To do this, add a new view, name it "Failure" or something similar, and in the Submit Settings of your form, choose your new view to show on failure. You can add text into this new view asking the user to refresh the page, or add an action button to bring them back to the form.