Solution 1:

The keylock indicator plugin for Xfce4 "shows the state of your keyboard LEDs: Caps, Scroll and Num Lock in Xfce panel."

Installation instructions for Xfce4 keylock indicator plugin:

(Note: This works on Xfce versions 4.6 and 4.8. Xfce 4.10 uses a different version of the libxfce4ui widget library and I haven't tested this plugin with 4.10).

EDIT: Tested and it works fine till Xfce versions 4.12.

  • Download the files from here.

  • Move to your download directory and unpack the files by running the following command:

    • sudo tar -jxf xfce4-kbdleds-plugin-0.0.6.tar.bz2
  • Next, change to the directory xfce4-kbdleds-plugin-0.0.6 and run these commands:

    ./configure --prefix=/usr
     make 
    sudo make install
    
  • Finally, add the plugin to your panel.

    -- The Add New Items dialogue can be opened by right clicking on an empty space on the panel and selecting Add New Items. If you right click on a space occupied by a panel plugin, you can access Add New Items by going to Panel → Add New Items.

Source