Mic Security - Protection against eavesdropping

I have a strained relationship with the Russian secret services, with the FSB. I use Android and the application to block the microphone from passive listening around the phone (for example, when the device is on a bedside table). But I would like to buy iphone. I know that it is possible to deny access to the microphone for applications but is not sure that there is a possibility or utility for a full lock, even if the microphone is needed. And incoming call automatically could unlock the microphone.