I found a new (to me) website which could be very helpful for research; AHN viewer.
It's a tool that shows the current height differences in the Netherlands. This allows you to look "under" the trees in a wooded area.
I have used this tool to have a look around Broekhuizen. I have attached a few screenshots. Sadly I couldn't find any other remains like craters or trenches, but it does clearly show the layout of the castle and farm, the lawn and the location of the former bridge entrance.
For those who want to have a look around. AHN viewer can be found here:
https://ahn.arcgisonline.nl/ahnviewer/
In the upper right corner you can turn different layers on and off . You can also make a layer transparant and combine more layers.
I am having the most luck with a combination of the 3rd and 5th layer (AHN3 "maaiveld dynamic" and "Hillshade".
The last picture attached is from Google maps showing the area.