These apps are not sure if it's compatible with a stylus.... Pls have a look and try it out !!
WritePad for iPhone, iPod touch, and iPad on the iTunes App Store
Notes Plus - Handwriting, Note Taking, Shape Drawing, and Sound Recording for iPad on the iTunes App Store
I picked up Notes Plus and have nothing but good praises for it. It's pricey but the features substantially validates the price. I love recording because it makes it easy to capture everything in a meeting.