No “the” sensor please, there are several models, please specify.
Not all are supported.
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Why? And how? Your phone hasn’t got an onboard zigbee controller.
And,
You can add the sensor to one zigbee controller only.
So, skip step 1 
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Again, you can add the sensor to one zigbee controller only.
When you put it in pairing mode, it gets removed from the zigbee mesh it was a part of.
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When it starts to blink, you’ll have to push the pair button every other second, to prevent it from going to sleep mode, until the device is added to Homey.
Keep the sensor very close, like 1cm, to Homey during the pairing process
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Pick one regarding to zigbee;
With the Homekitty app, you can have your Homey devices available in homekits.
KB info:
