Which Unicode characters do smilies like ٩(•̮̮̃•̃)۶ consist of?

"As for your confusion about multi-line: There are numerous diacritics at work here. Those are combining characters that get placed above or below other characters. If we dissect the specific smiley (●̮̮̃•̃) we get the following:

( U+0028 Left Parenthesis (this is obvious)

● U+25CF Black Circle (this will be the left eye)

̮ U+032E Combining breve below (this gets part of the mouth)
The fact that it's placed slightly right of the circle is a
font issue. Normally it should appear directly below the
preceding character

̮ U+032E Combining breve below (still part of the mouth)

̃ U+0303 Combining Tilde (this will be the left eyebrow)

• U+2022 Bullet (right eye)

̃ U+0303 Combining Tilde (eyebrow)

) U+0029 Right Parenthesis

It's some clever use of diacritic characters that creates the illusion of multiple lines here. Combining characters can be stacked, as seen with the breve, but usually the results are less good.

You can paste the smileys into Word and by placing the cursor after a character and pressing Alt+C you can cause the character to be replaced with its Unicode code point in hexadecimal. In the case of diacritics you first replace the diacritic and then can proceed with the base character (or still more diacritics if they are there). The other way around works too. You can enter 2022 and press Alt+C and get a bullet point.

So for getting the smiley above you can use the following string of letters and numbers:

002825CF032E032E0303202203030029

paste it into Word and hit Alt+C every four places, beginning at the left.

Note: In the preceding paragraphs I have used the hotkey Alt+C exclusively. When not using Word but instead some variant of RichEdit (for example in WordPad) this becomes Alt+X instead. Also, as mentioned in the comments, for some people apparently it's Alt+X in Word, too. In the interest of brevity I will only talk about Alt+C, but you should use whatever variant applies to you. Another method, mentioned in this answer would be to use Ctrl+Alt+Shift+F12 which seems to work as well. Just in case there aren't enough options yet.

Note 2: In the overview of characters used for the smiley above the spacing seems off in some places. This had technical reasons and may differ from one browser to another. Also some combining characters tended to disappear which is why some of them are shifted to the right."

If these are too complex, Unicode #263A (☺) and Unicode #2639 (☹) are supported by most OSes and browsers.