This new Google software is the most safest and user-friendly reCaptcha. Only when google suspects that user is a robot, then random reCaptcha will show up. Thanks to that, in most cases the customer does not have to waste time confirming that he or she is not a robot.
Easy installation! Simple and fast configuration. In configuration page provide pair of keys received from Google and save it. You can get your keys on this site: https://developers.google.com/recaptcha/docs/start
And that's it! Your contact form now is protect from spammers.