I would definitely say yes I have worked with a personal trainer. No man is an island. However, I can tell you what to say if that hasn’t been your experience.
If you haven’t then you haven’t.
On another note, I am unclear as to whether the individual posing the question is asking have you worked with a personal trainer in a collaborative manner or have you hired a personal trainer to help you reach a particular goal.
I’ve done both so I would respond in the affirmative.
My answer would be “yes.” As a professional trainer, we constantly take continuing education coursework in which much of it is interactive/instructional in nature. This alone would qualify as ‘working with a personal trainer’ in my opinion. Additionally, I train other trainers as well as we train together from time-to-time. So, under all of these training scenarios taken together, my answer to the question you posed would be “yes.”