How to use a JSON response?

Dear Flowable Gurus,
I am a newbie and just started to experiment with Flowable Opensource and external http-calls.

My current playground is the catfact API:
It returns a simpe random catfact as response:
{“fact”:“Unlike humans, cats cannot detect sweetness which likely explains why they are not drawn to it at all.”,“length”:102}

I was able to receive the JSON response using the ‘Http task’.
I set “Save response as JSON :” to true
The response is correctly saved into my variable “catfact” :muscle:
BTW: it took me a while to find out the the Activity throws errors when checking “Execute parallel in same transaction” !!!
But now I would like to access the properties of the JSON object for example: catfact.fact inside a Form expression ?
I also would like to use result of the response in Groovy scripts.

Many thanks for your help and best regards