In X-Plane 11.10, if a USB device presents the sim with either an axis, button, or hat switch, the sim will treat it like a joystick. If your Linux distro doesn’t recognize your joystick hardware as something that should be available to normal applications, including X-Plane, you will need to set up proper udev rules. Udev rules will prevent X-Plane from seeing the keyboard or mouse as “joysticks” and allow you to use your actual hardware with the sim.
Here are two helpful articles on setting up udev rules for X-Plane:
It is never recommended to launch X-Plane as root (via sudo)—always set up udev rules in order to run X-Plane as a normal user.