Muiderslot Castle and Zaanse Shans

Planning well you can do both in one day. For Zaanse Schans you have to take the train to Zaandijk Zaanse Schans and takes some 17 to 19 minutes. From the railway station you have to walk about 15 minutes to the entrance.

For Muiderslot you have to take the train to Weesp and needs about the same time from Amsterdam Centraal. But for the additional leg you have to take the bus “110” to Muiden Center and some 10 minutes walking to Muiderslot (slot is the Dutch name for castle)
https://muiderslot.nl/en/plan-your-visit/opening-hours-and-fees/

Know that the mills of Zaanse Schans will be out of service if there is no wind or is too strong. Can be worth taking in account during planning. Nevertheless they are open to visit as far as I know all year around. But read the following info about opening times.
https://www.dezaanseschans.nl/en/plan-your-visit/opening-hours/

Public transport is much more efficient in and around Amsterdam, a car is to my opinion more a nuisance. For planning public transport you can use there sites:
https://www.ns.nl/en
https://9292.nl/en/journeyadvice

My caution would be that a "half day" trip in the height of tourist season - the summer months - is a LOT different from a half day in the WINTER months. When the sun rises early and sets late, you can cram a lot of things into a day. But when the sun is late to rise and early to set, that window of opportunity is significantly shorter, so you may not have as much opportunity to get to both places.

Thank you!