Recently, the CyanogenMod team added support for call recording on certain devices in CM11 nightlies. However, because of privacy concerns and regional law restrictions, the team will not be providing users with an option to enable this feature. 

Thanks to an Xposed module from developer pyler though, CyanogenMod users can enable call recording functionality on their devices pretty easily. If you are already running Xposed framework, simply download and install this Xposed module. If not, install the framework from here first.

Once the module is installed, you will automatically see the call recording button at the bottom action bar of the call screen. You will have to tap that button to enable call recording as the module does not record all your calls by default.

Keep in mind that the module only works on CM11 nightlies from 14th August or the M10 build or later, and does not work on any other ROM that is based on AOSP.