As per Caro, internal audit is not compulsory for a company if:
1) the Company is not listed on any stock exchange or
2) the paid-up capital and reserves as at the commencement of the financial year did not exceed Rupees Fifty Lakhs or
3) the average annual turnover for a period of three consecutive financial years immediately preceding the financial year did not exceed Rupees Five Crores.
Hence, you have to find out whether your company comply with above. Futher, current years' turnover is irrelevant for deciding the applicability of CARO.