Eyesight is poor to non-existent, they sense by way of their antennae which continually tap the ground as the millipede moves along. They are very clean creatures spending a great deal of time cleaning and polishing the various parts of their bodies, and have a special brush-like group of hairs on the 2nd or 3rd pair of legs which are used in cleaning the antennae. This is important to provide bacteria and microfungi with more surface area to work on as they recycle organic matter in the soil. So, as with Woodlice, keep the areas around vulnerable plants free of debris. Not a major problem in the garden causing some damage to the roots of strawberries and cucumbers.
Sugar beet is the main crop to suffer from millipedes.
Their thick black cuticle makes chemical control difficult. Just crush them and remove debris where they can hide, from areas where you are growing seedlings.