Hi @liuxueliang and thanks for your query. The Tobii Eye Tracker 5 is principally intended for gaming and user interaction whilst the Tobii Pro devices are indeed produced for the user case you have provided. However you can obtain special advanced use licences for the ET5 when used in conjunctions with the appropriate SDK.
To obtain a quote for Tobii Pro trackers, please get in touch with your local sales representative @ https://www.tobiipro.com/contact/sales/
With further information on your intentions and programming experience, we would be better placed to assist you in this matter. Best Wishes.