Yes, you need to report.
If you charged rent at below fair rental price, it is not considered as a rental property for business. Instead, it is treated as a personal-use property, therefore, you do not report as a rental and thus no rental expenses are allowed for deductions.
However, you do need to report the income as other income on line 21 of your Form 1040. IRS considers this as a hobby and any related expenses up to the rental income may be deducted on Schedule A subject to 2% of your Adjusted Gross Income AGI.
If you charged at a fair rental price, you would report under Rental income and deduct related expenses on a Schedule E.