Hackers requesting money from me

Hi all , I have received an email claiming that my phone has been hacked into . The e-mail says I have been under their watch for months now , they further said they collected data about me and all activities I have been doing via my iphone , they say for them to delete all those data against me I must transfer load if money via Bitcoin account sent to me . I am dead worried about this because I have very sensitive data inside my device .

can some help on this regard . And also is there anyway I can check if my I phone is hacked into ?