There are some referential questions that you can follow as a guideline. However, you should definitely include some that apply to your workplace concretely. Look at your employees in the eyes and think to yourself: "What do I want to know about you?". But please, don't be creepy. This is supposed to be a way for everyone to feel more comfortable and happy in their job.
Some subjects to treat could be:
- How heard they feel.
- How aligned with the company's goals they are.
- How motivated and engaged they feel as per their work.
- Everything related to bonuses, the relationship between salary and performance, the workplace environment or the average level of satisfaction.
Keep in mind that, although generic, these are just some examples.