The ABSniffer 528 USB dongle is a ready-to-use nRF52 dongle with a very compact form factor. Its intended use is as a low-cost BLE sniffer that can sniff the advertisements of nearby devices. It features an NRF52832 chipset and a SiLabs CP2104 USB-to-serial converter.
This article shows how to write a custom iBeacon firmware for the nRF52 chipset and deploy it to an ABSniffer USB dongle.
You can configure the usb dongle over serial to change the advertising data easily. See the specifications for ABSniffer 528.