Open Settings > Hot Desks > Custom Booking Fields and click "Create New Custom Booking Form"

Name: This is for your reference only, enter a memorable name for the question
Type: This is a dropdown or Check Box, Text Box or Yes/No Field.
Field Label: This is the question you are asking the user when they book a Desk
Order: Leave blank for the system to order or enter values to force an order
Required Field: Check box that makes the question mandatory or not
- Restrict booking depending on value?: This is optional, if you select it you will see the option:
  - Answer must be the following to make the booking: Select what the correct answer is to allow bookings to be processed
Apply To Specific Offices: Open and select specific Offices or leave off for all Offices
Apply to Specific Desks: Open and select specific Desks or leave off for all Desks

You can repeat the above steps to create multiple questions, each question can be specific to certain Desks or Offices if you like.

Custom Booking Forms