It’s a very confusing post to read especially regarding who it was you were either talking to or messaging at the time - sounds like you were chatting to one person and messaging another. The director shouldn’t have snatched your phone off you but it sounds like he was already suspicious that you were talking to the person who had been ranting about him on social media otherwise, why did he ask to see you phone?
Was that person under a work suspension while under investigation for their post/s? Often people are told not to interact with their colleagues while they are on suspension so you messaging/chatting to them could be seen as a breach of that.
Unfortunately, if you have under 2 years of employment in a job, your protection from dismissal is limited pretty much to whether the reason for dismissal is down to a protected characteristic or not; if not, you’d struggle with a tribunal claim. Add in to that, being on probation, they can simply say you did not ‘fit’ with the company as a reason for dismissal. Then, being on a zero hours contract, they can simply stop allocating you any hours. I think you would find it very difficult to get anywhere with a complaint of unfair dismissal.
I think the most you can expect would be notice pay based on whatever is in your contract (usually 1 week especially early in a job unless specifically mentioned) but, being on a 0 hours contract, it may be you’re not due anything.
If it was me, it sounds like the director wasn’t a nice person to work with and I would be thanking my lucky stars to be out of there - but not if it meant being unemployed and with a dismissal added to your record, along with likely no positive reference to take with you!