Execute script on external keyboard connection

Question

EDIT: This is NOT a duplicate because the linked question is about external USB drives, not keyboards. The suggested command udevadm info -a -n sdb does nothing in helping to find the corresponding attributes for the keyboard.

After spending more than an hour on this, eventually I tried the following, which is unlikely to be accurate:

SUBSYSTEMS="input", RUN+="/home/jx/Dropbox/scripts/keyboard.sh %p"
SUBSYSTEMS="hid", RUN+="/home/jx/Dropbox/scripts/keyboard.sh %p"
SUBSYSTEMS="usb", RUN+="/home/jx/Dropbox/scripts/keyboard.sh %p"

However, it only worked when I first start up the computer. Whenever I unplug the keyboard and reconnect it later, the script doesn't get executed automatically.

How can I find the attributes for the keyboard and how do I ensure the script gets every time the keyboard is connected, even when the OS is already running?

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I'm performing two modifications on my keyboard on startup:

xset r rate 160 50 
setxkbmap -option "ctrl:nocaps"

However, they seem to be lost whenever I disconnect my external USB keyboard (sometimes I switch the keyboard between machines), and I always have to re-execute the commands whenever I reconnect it, which is quite annoying.

Is there a way to let the system detect the keyboard connection event and execute a custom script upon it?

Or maybe, alternatively, find a way to keep those two settings permanent even after restart.

I am on Arch Linux with systemd.