The expression you are looking for is '수고했어요'
수고- means hard work, trouble or effort (however it's not commonly used on its own)
So you have worked hard or you did work hard is 수고했어요 or also could say 수고하셨습니다 to be even more polite
This is a fixed expression and is commonly used, however do not use it with people much older than you as it could seem to be rude
Hope this helps^^