Hi yaozhao,
This would be two separate questions. "Are you retired?" would be a Multiple Choice, Single Answer question.
The "If yes, what year did you retire?" question be a Text Entry, Single Answer question. Use Display Logic so if only appears if Yes is selected in the previous question. Qualtrics doesn't have a way to combine a checkbox with a Text Entry field, so to accommodate those who don't recall when they retired, I would instead instruct them to leave the Text Entry field blank (e.g. "If you do not recall what year you retired, leave the field blank."