Clone the source repositories from GitHub:

# git clone https://github.com/ddccontrol/ddccontrol.git
# git clone https://github.com/ddccontrol/ddccontrol-db.git

You should now have two directories, ddccontrol and ddccontrol-db.

Alternatively, download the latest source tarballs from the releases page and unpack them with:

# tar xvfz ddccontrol-X.Y.tar.gz
# tar xvfz ddccontrol-db-YYYYMMDD.tar.gz