Ah, but a schwa is used in unstressed syllables. If your word is a one-syllable word, then you necessarily put stress on the vowel. The symbol you want here is a caret (^). To be precise (since you asked!), it's an open-mid back unrounded vowel.
Open-mid: This refers to the height of your tongue: basically open, mid, and closed. Closed vowels are ones where your tongue is high in your mouth (the vowel sound in "tea"), closing off the passage of air. Open is the opposite, where your tongue is low and mouth is open (the vowel sound in "spa"). So, open-mid is somewhere where the tongue is pretty low in the mouth, but not quite what we would call open.
Back: This refers to tongue positioning: front, central and back. The sound you are looking for is a back vowel, because your tongue is far back in your mouth when you make it. This is compared to a vowel sound like the one in "bed".
Unrounded: Some vowels are given a different sound by you rounding your lips (like the vowel sounds in "boot" and "coat"). Try saying the ^ sound that you are using and then slowly round your lips as you say it. The sound changes, so that you go from saying the word "cut" to the word "caught".
Maybe that was far more information than you needed, but hope it helps!