I used following code snippet to get financial dimension attached with hcmposition
static void GetFinancialDimensionValue1(Args _args)
{
HcmPosition position;
HcmPositionDefaultDimension positionDefaultDimention;
DimensionAttributeValueSetStorage dimStorage;
Counter i;
select * from position
join * from positionDefaultDimention
where position.PositionId=="000001"
&& position.RecId == positionDefaultDimention.Position;
dimStorage = DimensionAttributeValueSetStorage::find(positionDefaultDimention.DefaultDimension);
for (i=1 ; i<= dimStorage.elements() ; i++)
{
info(strFmt("%1 = %2", DimensionAttribute::find(dimStorage.getAttributeByIndex(i)).Name,
dimStorage.getDisplayValueByIndex(i)));
}
}

Reference: https://jkmsdax2012.wordpress.com/2015/11/16/how-to-get-financial-dimensions-for-a-particular-customer-using-x-code-in-ax-2012/