I'm not sure I understand what you're trying to do?
You want the particle to move along the path and orbit around it? like, move along a spiral along your path?
Or maybe stretch the particle so one end touches the path and the other end points away from it along a vector orthogonal to the path, and rotates around it?
There are actually an infinite number of "normal" axes at any point on a path (when plotted, they form a circle, whose disk is perpendicular to the path at that point), and 'sampleNormal' returns the normal of the shape swept along the path, if you have no shape, it will return zero.
What you're looking for is probably 'path.axisUp', 'path.axisSide', or 'path.axisForward' ? these represent the 3D coordinate frame along the path, based on the path rotations created in the 3D package that was used to export the path.