Amazon.com: NC Nunchuck Controller Joystick Gamepad Replacement for wii Nunchuck Controller, Compatible with Nintendo Wii & Wii U Video Game Gamepads (White 1PCS) : Video Games
Pinout - Wii Nunchuk
Extenmote: NES, SNES, N64 or Gamecube controller on Wii or Wii U via the Wiimote.
Use Wii Nunchucks with Raspberry Pi — The MagPi magazine