Steps

• Install package - npm i react-google-recaptcha
• Get the test site key from google documentation

Behaviour

• Check the implementation in App.js
• Captcha includes the following two listeners among others - onChange and onExpired.
• When user clicks on a captcha, onChange gets fired and a token is passed to the onChange function in place of the event object.
• After about 90s the same token gets expired. The checkbox gets unchecked and event object returns undefined.

Reference

• Youtube