ReCaptcha v2 for Contact Form 7 
ReCaptcha v2 for Contact Form 7 is used by 0.01% of sites
Official Website
https://wordpress.org/plugins/wpcf7-recaptcha/Category
WordPress pluginsContact Form 7 v5.1 dropped support for reCaptcha v2 along with the [recaptcha] tag December 2018. This plugin brings that functionality back from Contact Form 7 5.0.5 and re-adds the [recaptcha] tag.