Usually, simulation tools allow visualizing the fields that are simulated.
For example, for capacitive coupling, electric field lines would tell where capacitance is coming from (in finite element or finite difference method based tools), or a surface charge density (in boundary element tools).
Very often just viewing the structure - in 2D (top view, layout / GDS file, etc.) or 3D - is useful to understand the sources of capacitive coupling. Capacitance is very deeply related to the geometry.
Magnetic coupling is a more difficult thing, it depends not only on the geometry, but also on the direction of the current flow, return path, current loops, etc.
In IC design flow, parasitic extraction tools can generate distributed RC model/network, and analyzing it may help understand parasitics (R, C, L, ...) and their root causes.
Max