As far as I know "koko ni oide" means "come here", but what does "to" add to the sentence "koko ni oide to". The context of the phrase is
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This と is a simple quotative-と, and this sentence is a typical example of a rhetoric device called 転置法 (hyperbaton) or 倒置法 (anastrophe). This is very common in Japanese poetry/slogans/lyrics because the grammatical role of a word is mainly expressed by the particle type rather than the word order.
Semantically this sentence is the same as 今、 ｢ここにおいで｣とあなたの声が聴こえる, where ここにおいで is the content of the voice which was heard by the speaker. The original sentence sounds more dramatic because of the reversed word order.