The net force on a body is $\mathbf F = m\mathbf a$. If friction is small for example, an object can slide along the inclined plane with an acceleration. The net force has the same direction.
But another concept of force relates it to elastic deformation instead of acceleration: $\mathbf F = k\mathbf x$. A perfect cubic object, lying in the ground by its own weight, has the vertical dimension smaller than the other two due to that elastic deformation.
If it is lying on a wedge, there is a reduction in the dimension in the normal direction ($\mathbf N = k\mathbf x$), and an angular deformation. The later is a measure of the couple caused because the friction force is not applied in the center of mass.
The forces can be measured by strain gages attached to the cube. Small deformations produce electric signals proportional to them. It is the principle behind most load cells.