Many graphics editors nowadays support some kind of bitmap/raster to vector conversion function (it is marketed with all kinds of names), which should also work for jpg to dxf conversion. You can even find dedicated utilities such as Img2CAD, which as specially designed for conversion of scanned drawings, maps and images (like JPEG) into accurate vector files, including DXF format.
Open JPG file Open DXF fileA 2D Design is drawing and design tool
A graphics conversion program
A 3D CAD translation software
A software used to geocode pictures
A CAD CGM converter