We use a baby monitor with camera. The camera works in the dark. This lets us see and hear our ladies any time of day from the comfort of our home. We have a hand-held receiver/monitor in the house. This does not connect to a computer. I see some for about $60 on Amazon, though we paid less at a discount store.
I think they tell you how they set it up. Also on here, I think it is 'confederate money farm' (a dot com) or similar who is on the forum here, cannot remember screen name -- maybe google it and find info.