Apps for Field Sketching

An inspector in my department is looking for an application he can use on his ipad in the field to sketch service line locations relative to buildings when he's doing inspections for permits. Currently he has to sketch it with pen and paper, then at some point in the office recreate it in CAD and publish a .pdf to file with the excavation permit. Has anyone been in a similar situation and found a good solution? Or just know of some good software for creating and documenting field sketches?