Pull the repo with sudo docker pull wpscanteam/wpscan
Start WPScan either directly
sudo docker run wpscanteam/wpscan wpscan -u http://yourblog.com [options]
or in the container:
sudo docker run -t -i wpscanteam/wpscan bash
# wpscan -u http://yourblog.com [options]
For the available Options, please see https://github.com/wpscanteam/wpscan#wpscan-arguments