This tiny app can detect the chipset of your iPhone. For iPhone 6s / 6s Plus, it can also detect the manufactory (TSMC or Samsung) of the A9 chip.
The compiled (and signed) binary file that I distrubte would upload the chip model, device type info and a unique id (not UDID, SN or IMEI) to my server, but it's for statistics only. Therefore, I can't identify you from these information. The statistic result is here.
Open http://demo.hiraku.tw/CPUIdentifier on your iPhone 6s/6s Plus, and follow the introduction to install.
Ars Technica: Chipworks: Both Samsung and TSMC are making the A9 chip for Apple
I'm a iOS jailbreak tweaks developer. You can find me on my twitter @hirakujira.