Cyanogen Inc with the introduction of its Cyanogen OS 12.1.1 update has now baked in Microsoft Cortana support. Meaning, Cortana has now been deeply integrated in this version of Cyanogen OS. This update is only available for the OnePlus One for the movement and might expand to other devices too, however, it is not confirmed that which device is it going to be next.
After this update, you can use the hotword “Hey Cortana” to activate the feature and it is by default on the “always listening” mode meaning that you can use this hotword from any screen, just like Google Now. However, for now, Cortana is not as flexible and powerful as the Google Now but it’ll be updated in the future to support and do more things.
Looking at the update, it is only available in the US for now and Cortana can also be uninstalled after the update if you don’t like it. And also, this update doesn’t bring Marshmallow with it, it’s still Lollipop so, we think that the people who are very keen to see the Marshmallow update hitting the OnePlus One have to wait a bit more to get it.
Source: Cyanogen Blog