The 20-year-old will join up with Chris Wilder's squad next week as he is currently away on international duty with Wales Under-21s.
Doble, who scored one goal in three appearances during a recent spell at Stockport, gives Wilder an extra attacking option following Jack Midson's move to Barnet.
The Abergavenny-born frontman is set to feature for Wales in their European Under-21 Championship qualifier against Andorra next Tuesday.
Source: PA
Source: PA