I want to convert regular forms let's say for example a rectangle and circle to a hand-written looking forms using Illustrator or Inkscape(best scenario). I don't want to use the pencil to draw the shape using the mouse.
Here is a an image that illustrate better the desired result:
As CAI said you can use different brushes for the line style to give a more hand-drawn effect which works well but that is only half the solution.
To fully complete the look use the warp tool (shift+R) or one of the warp or distort effects or possibly a combination of the above. This will give the imperfects needed for a more authentic hand-drawn look.
In Inkscape you can do this with path effects, simply use the circle tool to create your circle, convert the object to a path and then use the path effect editor to create your effect.
