I‘ve Apple Keyboard with Numeric Keypad and it is not working whenever I connect to my HP laptop. How do I use this keyboard under Debian or any Linux distribution?

The Apple usb keyboard is fully supported under Linux, you need to load the driver called hid_apple (in most cases it get loaded automatically), if not loaded, type the following command at shell prompt as root user:
# modprobe hid_apple

And you will see something as follows in your log file:
tail -f /var/log/messages
Sample outputs:

Jun 14 06:52:53 laptop kernel: [    3.957031] input: Apple, Inc Apple Keyboard as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.2/2-1.5.2.2/2-1.5.2.2:1.0/input/input7
Jun 14 06:52:53 laptop kernel: [    3.957254] apple 0003:05AC:0220.0003: input,hidraw2: USB HID v1.11 Keyboard [Apple, Inc Apple Keyboard] on usb-0000:00:1d.0-1.5.2.2/input0

Now you can use your keyboard with desktop or Laptop running the Linux operating systems.