If you have a photo a person, can you input it into CAD?

Short answer: yes. However, there are a few ways to do this depending on the type of results you want. My expertise is in AutoCAD, so my answer refers to this program.

AutoCAD can import image files. I know for a fact you can import TIFF, JPG, PDF, BITMAP, GIF, and a few others. They will not be part of the DWG file but will be an external reference (xref). Once saved, every time you open the drawing file, the image will open with it, provided the file location stays the same or is in the same folder as the drawing. AutoCAD has limited ways you can manipulate the image, so it is important to get the image the way you want it before importing it. AutoCAD will allow you to adjust the brightness, contrast, invert, and control transparency among a few others.

If you want it to be an actual CAD file, you can either trace the image with vectors in CAD or use an add on program that will allow for hybrid files.