The Galaxy Note II and its tablet big brother the Galaxy Note 10.1 were both released in 2012. That being the case, the odds of them getting an Android 6.0 update are about as good as the Chicago Cubs winning the Super Bowl. Of course, a lack of updates (even for hardware that might not meet the minimum requirements) is a big part of what makes custom ROMs so popular. So it is that the CyanogenMod ROM's version 13, based on AOSP code for Marshmallow, has come to a handful of older Samsung devices.
First on the docket is the Verizon version of the Galaxy Note 10.1, Samsung's first effort to bring its Note stylus features to a tablet format. The CyanogenMod build server has been spitting out nightly versions of CM13 for the tablet for the last few days. The same is true for the GSM-LTE version of the Galaxy Note II, along with the Verizon and Sprint versions. Users will need a custom recovery and an unlocked bootloader to flash the ROMs, which might require some third-party tools in the case of the carrier hardware versions.
Remember that these are nightly builds, so even in the case of the normally reliable CyanogenMod, they might have considerable bugs or missing features. It could be best to wait for a more stable version... though there's no guarantee that one will be released. If you're ready to pull the trigger, download the ROMs and grab a copy of Gapps for the Play Store and Google services.
It looks like the Xiaomi Redmi 2, oddly labelled as the WT88047, is also getting CM13 nightlies.