visualCaptcha is a free wordpress plugin and it provides secure Captcha with images instead of text and drag & drop capabilities with mobile-friendly.
Main features:
Mobile-friendly
Accessible
Retina-ready
Secure
Customizable
To install visualCaptcha
Login to wordpress (wp-admin).
In your admin dashboard click plugins and select Add New.
Type visualCaptcha in the search field and click Search Plugins button.
Install visualCaptcha.
After the successfully Installation click the activate Plugin link to activate the plugin.
[OR]
Download visualCaptcha wordpress plugin. Download link
Unzip and upload it to your WordPress wp-content/plugins directory.
Login to wp-admin. In your admin dashboard click plugins and activate the visualCaptcha wordpress plugin.