Here are instructions to install Nethunter (as a ROM) with working native monitor mode in the chroot using Nexmon. The ROM is a modified CM 14.1 (nougat) base with custom kernel which supports: HID, Drivedroid, Kexec, and external wireless.
You will need the following 3 items (maybe 4):
- TWRP for Hammerhead-CAF: https://dl.twrp.me/hammerheadcaf/twrp-3.0.2-0-hammerheadcaf.img.html
- Nethunter OS (based on CM 14.1): https://build.nethunter.com/nethunteros/CM14_1/hammerheadcaf/nh-14.1-nethunter-hammerheadcaf-v1.zip