Can Someone Hack into Your Computer Using Your Ip Address?

Someone recently told me that they hacked into my computer and iPhone using my IP address. They were able to download my iMessages, emails, and as far as Instagram messages, and Spotify info onto a server and read through personal messages from a specific time period. They also said they were able to access this because I was connect to their internet network. Is this possible? If it is possible, how much and what sort of information would they have been able to retrieve?