How can I check whether the grid that I have is aligned to the segmented volume and to the sensor gradiometer?

Having a source model (i.e., positions of the dipoles), a head model (i.e., volume conduction model of the head), and the ‘grad’ structure, (i.e., information of the gradiometers) you can use the following:

hold on
ft_plot_mesh(sourcemodel);
ft_plot_headmodel(headmodel);
ft_plot_sens(grad);