Cyanogenmod 12: How to display calendar events on lock screen?
The app you are looking for is cLock. Its a widget and its still present in CyanogenMod.

Unfortunatelly, from Lollipop onwards, you can't put any widgets on your lock screen, and by that you are unable to use the described widget as you used it before.

Hovever, you can still place it on your home screen.