On Linux with a mounted /proc file system, you can find the command line parameters from /proc/$$/cmdline.
But this (and the proposed %^C) would be tricky. Command line parameters maybe clustered. Searching for just '-F' won't do, the parameter may be passed as '-wF:', which sets the split pattern to :. However, a parameter '-iF:' won't.
And then there is PERL5OPT.
In that case, you rather want an array of pairs instead of a hash. There are switches that can be used multiple times (-M, among others), and some switches interact and their order is relevant (-l and -0 for instance).