tax probelm for rent, please

I rent my apartment to a lady who is a self empolyment. She pays rent to me in cash but reports partial rent to her business expense. If i do not report this rent as my imcome, whether will IRS find my fraud because the lady indicates my apartment address as her business adress. How large amount Tax fraud would go to criminal trail ( i heard that it is 10,000USD, is it true).
Thank you for your time.

Your every information and advice are highly apprecaited.
Ganren