What is LineageOS ?
In December 2016 Cyanogen Inc announced that it will discontinue all its services by 31 Dec 2016 but the Open Source CyanogenMod project will remain and it will be renamed as LineageOS
The Unofficial build of LineageOS is now available for OnePlus 2 , You can download and flash the ROM from below
To Flash Custom ROMs Your Bootloader Must Be Unlocked & You Should Have A TWRP Recovery
Don’t forget to make a backup !
Boot into TWRP
Install ROM zip