Sure, just run PCR (polymerase works on DNA only). If you get PCR product, DNA is there. In case, your sample is not RNA, but cDNA (after reverse transcription), run your PCR using primers recognizing any intron (provided you have eukaryotic sample).

As Martin said you can run a PCR. I like to choose primers to a gene that has many copies, and that would generate a small amplicon.

Or you can run the RNA sample on an agarose gel and visualize the RNA by ethidium bromide staining. Genomic DNA is typically much larger than RNA and can be visualized as a higher molecular weight band, while RNA will form a smeared band in the gel.

You can also do a Qubit HS for DNA in your RNA sample

Thanks you vary much for your answers.