Google reCAPTCHA

Google’s reCAPTCHA is a popular solution for verifying that form submissions are from real users.

Go to Google reCAPTCHA Admin to create a new app.
Choose reCAPTCHA v2 > "I'm not a robot" Checkbox (or whichever suits your needs).
Copy the provided Site Key and Secret Key.
In your admin panel, navigate to Admin > Settings > Security > Captcha.
Select Google reCAPTCHA as the Captcha Driver, then paste your Site Key and Secret Key in the fields provided.