Where they can use the information as evidence depends on whether you were in custody as per Nolo:
When Is a Miranda Warning Required?
It doesn't matter whether an interrogation occurs in a jail, at the scene of a crime, on a busy downtown street, or in the middle of an open field: If a person is
in custody (not free to leave, whether or not handcuffs are involved), the police must read the
Miranda rights if they want to ask questions and use the answers as evidence at trial.
Not in Custody; No Miranda Warning Required
If someone isn't in police custody, no
Miranda warning is required and anything the person says can be used at trial. Police officers often avoid arresting people—and make it clear to them that they're free to go—precisely so they don't have to give the
Miranda warning. Then they can arrest the suspect after getting the incriminating statement they wanted all along.
Police only need to provide Miranda warnings in certain situations. Learn when Miranda rights are required and what happens if police don't follow the law.
www.nolo.com
I am not an attorney and this is not legal advice. I found the "not in custody" information interesting.