The Ubuntu Kernel Team has rebased Ubuntu 15.10 Wily Werewolf on the Linux Kernel 4.2 RC5, which has been released a few days ago by Linus Torvalds.
Most likely, the final version of Ubuntu 15.10, scheduled for release on the 22nd of October 2015, will be using Kernel 4.2 stable.
For now, Ubuntu 15.10 has reached its alpha version only, but the final beta system is expected to arrive on the 24th of September, this year.
If you want to install Kernel 4.2 RC5 on your Ubuntu system, follow the instructions from this article.