This app was mentioned in 4 comments, with an average of 1.00 upvote
Ever check if your phone has ANT+ compatibility? If so, you can download the ANT+ Plugin. There should be a multitude of apps that will show your ant+ hr readings.
I know you asked for ANT+, but for a while, I used the Bluetooth on my Tickr to read my HR with the Wahoo Runfit app on my phone.
I guess not all smartphones are cabable of this, but some geocaches use "chirp" for this. It's 10m and not 10 feet, but i guess this could be a starting point for some research.
https://buy.garmin.com/en-US/US/shop-by-accessories/geocaching/chirp-/prod74811.html
An App that can find them: https://play.google.com/store/apps/details?id=com.dsi.ant.plugins.antplus
If you are using ANT+ devices you need to install the ANT+ client which can be found here:
https://play.google.com/store/apps/details?id=com.dsi.ant.plugins.antplus&hl=en
It uses your GPS to track and map the ride and coarse speed/elevation details. If you are using ANT+ or Bluetooth cadence/speed, Heart Rate Monitor (HRM) or power meter then you need to synch it to IpBike and create a profile for the device.
This is the official site for it and should have all the details on how to use it a lot better than I can type out: