When the OnePlus One came out of the box it was with CyanogenMod pre-installed. The ROM developer's outspoken CEO, Kirk McMaster, said that it was his company's software that was responsible for OnePlus' success. "Essentially they built their brand on the back of Cyanogen," McMaster said. But Cyanogen soon signed a deal to be exclusively on Micromax devices in India. This happened just as OnePlus was moving into the country, and led to a lawsuit that initially banned the OnePlus One from stores in India. That ban was eventually overturned.
When the OnePlus 2 was launched, it did so with OxygenOS pre-installed. But now, according to the Git repository, it appears that OnePlus 2 users will soon have the opportunity to flash CM on their phones. Unlike the OnePlus One, those with the newer model will have to root their handset in order to install the ROM. That could lead owners of the device to void their warranty.
If you do decide to flash CM on your OnePlus 2, you will have two choices. Version 12.2 is based on Android 5.1 and version 13 is based on Android 6.0.
Source : CyanogenMod