1. A method comprising: a) providing one or more coded oligonucleotide probes, each coded oligonucleotide probe comprising an oligonucleotide associated with at least one nanocode comprising a detectable non-encoding feature; b) contacting a target nucleic acid with the one or more coded oligonucleotide probes; and c) identifying coded oligonucleotide probes that bind to the target nucleic acid using scanning probe microscopy (SPM) to detect the nanocode and the detectable non-encoding feature.