Iphone Remote Controlled

My phones acting up and i believe someones remotley controlling it, they kept tyring to input my password and when that failied i ereased my phone after doing so had a minute were it worked to which they are back at trying to gain access and seems to only stop if i turn off the phone but as soon as i open it back up they are onto me again.

Any help i have not been on any websites that could have caused this that i know off so i have no clue why this is happening.