How can I type the unicode character U+200B (zero-width space character) with my keyboard?
First convert the hex 200B to decimal 8203
Second, making sure numlock is turned on, press the following keystrokes while holding down the Alt key, then striking the four digits on the numeric keypad, and finally releasing the Alt key.
It will insert the proper character, but you may see garbage depending on the font you are using (does it contain a glyph for that character) as well as the editor you are using may not be unicode aware and treat it as two characters or something else completely.
Note: I tested this with the Arial Unicode MS font, and it worked like a champ.
To type this on a laptop with no separate number pad, you'll need to turn numlock on, which will differ depending on your computer's manufacturer. The numbers 0-9 are then MJKLUIO789, respectively. On most laptops, these keys are marked as such. But, even if they aren't, it should still work.