Sorry, I don't have an F800 nor any Thinkware dashcam so unless somebody comes up with a definite cable then you might have to experiment.
I have a Viofo A119 V3 which I mounted on the front screen but wanted a shorter cable than the standard one. As I just drape the cable from the rearview mirror to the centre console I only needed a cable that was 1 metre in length. I had a look on Amazon and found one that was 1 metre, a mini USB, and that had plenty of good ratings so I bought the following:
The above cable works well and cost me £5.99. I know that the above is no good to you as it's Mini and not a Micro but if you check Amazon and look for a power/data cable of the length that you need and which has a lot of good reviews then it's worth a gamble and should work.