There are are a few definitions/calculations of magnetic moments. The easiest is defined with respect to torque aligning to an external field. So, the easiest way to calculate the dipole moment is to apply an external field (or use a Helmholtz coil to create a uniform field around the object), and then calculate the torque vs angle around the center of the object/assembly. So, first you might try to create a uniform field without any objects, for which you could use a Helmholtz coil arrangement. Or you could use a combination of boundary conditions (Tangential H-field to define the direction tangent, and Zero Tangent to define the ends where the flux enters/exits the domain). Then insert the geometry, and use a Torque parameter on the entire assembly to calculate the T = m x B moment torque.